The invention pertains to signal jamming systems, carried by manned or unmanned aircraft including missiles, for the avoidance of position locating, tracking and fire control radar.
The present application is related to the subject matter of U.S. application Ser. No. 225,669, filed Jan. 16, 1981, by Walter E. Buehler, Roger M. Whitson and Michael J. Lewis, for ANTI SIGNAL-INTEGRATION APPARATUS AND METHOD FOR COUNTERING INTEGRATION ENHANCEMENT OF RADAR RETURN SIGNALS MASKED BY AIRBORNE VENTRILOQUAL-LIKE NOISE JAMMING.
The use of radar signal jamming equipment carried onboard manned and unmanned aircraft to mask the aircraft's position from position locating, tracking and fire (weaponry) control radar is one of a number of known radar avoidance techniques that fall in the broader field of electronic counter measures (ECMs). Existing jamming techniques are primarily effective in denying the radar equipment range information, i.e., the distance between the radar and the target aircraft. However, the transmission of the jamming signal, emanating as it does from the aircraft, enables some radar systems to home-in on the source of the jamming signal, which is typically a noise signal in the frequency band of the radar, and thereby acquire accurate information representing the angular position of the aircraft. This angle information alone, even without range determination, is sufficient to allow for many types of weaponry, aimed by fire control radar, to reach and destroy the target aircraft. Thus, the mere generation and transmission of a noise jamming signal is not totally effective and providing the desired masking of the aircraft to the tracking radar.
Accordingly, an object of the invention is to provide a system for generating and radiating a radar jamming signal from a target aircraft that is to be masked from the radar in such a manner that the jamming signal deceptively emanates from a position which is removed at a safe distance from the target aircraft.
More particularly, it is an object of the invention to provide an apparatus for transmitting an onboard generated jamming signal over a transmission line towed by the target aircraft, and radiating the jamming signal from a passive radiator attached to a trailing end of the transmission line. A related object is to provide such a towed transmission line for the jamming signal which is capable of transmitting the jamming signal efficiently over the relatively long distance needed to dispose the point of signal radiation at a safe distance from the target aircraft, and to employ a line having transmission characteristics that preclude excessive radiation leakage at the leading end and along intermediate sections of the line which, if allowed to occur, would cause the emission of a radar trackable signal source at positions dangerously close to the target aircraft.
Still another object is to provide a transmission line for the above-mentioned ventriloqual-like radar jamming system, that has high efficiency so as to enable sufficient signal power to reach the radiator at the trailing end of the line so that a jamming signal of adequate strength can be radiated to effectively mask the target aircraft.
In accordance with the foregoing objects, it is a feature of the invention to employ a single wire transmission line, which characteristically provides highly efficient signal transmission when in free space or air and to tow such line behind the target aircraft. In connection with this feature, it is another object to provide a broadband, highly efficient, nonleaking electromagnetic wave launcher for launching the onboard generated jamming signals onto the leading end of the towed single wire transmission line.
It is also a feature to provide a single wire transmission line that is constructed to accommodate efficient surface wave transmission and that is also sufficiently flexible to allow it to be wound onto and unwound from a line stowage reel carried onboard the target aircraft.
A further feature is to provide a radiator in the form of a drogue for attachment to the trailing end of the line for radiating and selectively polarizing the thusly radiated jamming signal, and for causing stable trailing flight of the line consistent with efficient transmission of the jamming signal wave energy along the line.